8
Q:

# A water tank is two-fifth full.Pipe A can fill a tank in 10 minutes and pipe B can empty it in 6 minutes.If both the pipes are open,how long will it take to empty or fill the tank completely?

 A) 6 min.to empty B) 6 min.to fill C) 9 min.to empty D) 9 min.to fill

Explanation:

Clearly,pipe B is faster than pipe A and so,the tank will be emptied.

part to be emptied = 2/5

part emptied by (A+B) in 1 minute=$\inline \fn_jvn {\color{Black}\left ( \frac{1}{6}-\frac{1}{10} \right )=\frac{1}{15}}$

$\inline \fn_jvn \Rightarrow \frac{1}{15}:\frac{2}{5}::1:x$

$\inline \fn_jvn \Rightarrow \frac{2}{5}\times 15=6mins$

so, the tank will be emptied in 6 min

Q:

A Tank is normally filled in 9 hours but takes four hours longer to fill because of a leak in its bottom. If the tank is full, the leak will empty it in ?

 A) 32.5 hrs B) 29.25 hrs C) 30.30 hrs D) 31 hrs

Explanation:

Let the leak will empty the tank in x hrs

Then,

1/9 - 1/x = 1/13

x = 29.25 hrs

2 2
Q:

A tap can fill a tank in 6 hours. After half the tank is filled three more similar taps are opened. What is the total time taken to fill the tank completely ?

 A) 4 hrs 15 min B) 3 hrs 24 min C) 4 hrs 51 min D) 3 hrs 45 min

Explanation:

Time taken by one tap to fill half of the tank = 3 hrs.

Part filled by the taps in 1 hour = 4 x 1/6 = 2/3

Remaining part = 1 - 1/2 = 1/2

2/3 : 1/2 :: 1 : p

p = 1/2 x 1 x 3/2 = 3/4 hrs. i.e., 45 min

So, total time taken = 3 hrs 45 min.

3 167
Q:

A large tanker can be filled by two pipes A and B in 60 and 40 minutes respectively. How many minutes will it take to fill the tanker from empty state if B is used for half the time and A and B fill it together for the other half ?

 A) 31 min B) 29 min C) 28 min D) 30 min

Explanation:

Part filled by (A + B) in 1 minute = (1/60 + 1/40) = 1/24
Suppose the tank is filled in x minutes.
Then, x/2(1/24 + 1/40) = 1
(x/2) x (1/15) = 1 => x = 30 min.

2 91
Q:

A tank is filled in eight hours by three pipes K, L and M. Pipe K is twice as fast as pipe L, and L is twice as fast as M. How much time will pipe L alone take to fill the tank ?

 A) 32 hrs B) 24 hrs C) 28 hrs D) 26 hrs

Explanation:

1/K + 1/L + 1/M = 1/8 (Given)
Also given that K = 2L and L = 2M
=> 1/2L + 1/L + 2/L = 1/8
=> (1 + 2 + 4)/2L = 1/8
=> 2L/7 = 8
=> L = 28 hours.

1 86
Q:

Two pipes A and B can fill a tank in 15 min and 20 min respectively. Both the pipes are opened together but after 4 min, pipe A is turned off. What is the total time required to fill the tank ?

 A) 15 min 20 sec. B) 16 min 40 sec. C) 13 min 10 sec. D) 14 min 40 sec.

Explanation:

Part filled in 4 minutes = 4(1/15 + 1/20) = 7/15

Remaining part = 1 - 7/15 = 8/15

Part filled by B in 1 minute = 1/20

1/20 : 8/15 :: 1 : k

k = 8/15 x 1 x 20 = 10 2/3 min = 10 min 40 sec.

The tank will be full in (4 min. + 10 min. 40 sec) = 14 min 40 sec.